Liquid crystal display

ABSTRACT

A display device includes a display panel including a first substrate and a second substrate; a source driver flexible film attached to the second substrate; a source driver circuit attached to the source driver flexible film; a common voltage line connected to the source driver circuit; common voltage compensation circuits connected to the common voltage line; and common voltage supply lines and common voltage feedback lines connecting the common voltage line and the common voltage compensation circuits, respectively, wherein the common voltage compensation circuits include a circuit line extending at a rear of the display panel connecting to a connection terminal on the source driver circuit.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the Korean Patent Application No.10-2014-0164800 filed on Nov. 24, 2014, which is hereby incorporated byreference for all purposes as if fully set forth herein.

BACKGROUND Field of the Disclosure

The present invention relates to a liquid crystal display.

Discussion of the Related Art

A liquid crystal display device has been more commonly used because ofits characteristics such as lightweight, thin profile, low powerconsumption, and low power driving. For example, the liquid crystaldisplay device is widely applied to portable computers such as notebookPC, office automation devices, audio/video devices, and indoor andoutdoor advertising display devices. The liquid crystal display devicedisplays images by controlling an electric field applied to a liquidcrystal layer to modulate light transmitted from a backlight unit.

FIG. 1 is an exemplary view illustrating a liquid crystal display of theprior art. Referring to FIG. 1, the liquid crystal display includes gatelines, data lines, a display panel 1, which includes a common voltageline VcomL, gate driving circuits 2 supplying gate signals to the gatelines, gate flexible films 3 on which the gate driving circuits 2 aremounted, source driving circuits 4 supplying data voltages to the datalines, source flexible films 5 on which the source driving circuits 4are mounted, a common voltage compensator 6 supplying a compensatedcommon voltage to the common voltage line VcomL, and a source printedcircuit board 7 on which the common voltage compensator 6 is mounted.

The display panel 1 includes pixels displaying images. Each of thepixels modulates light entering from a backlight unit (not shown) bydriving a liquid crystal of a liquid crystal layer through an electricfield between the data voltage supplied to a pixel electrode and thecommon voltage supplied to a common electrode.

The common voltage compensator 6 may include a plurality of commonvoltage compensation circuits 6 a, 6 b, 6 c, and 6 d. The common voltagemay be affected by unspecified noise generated in the display panel 1.The common voltage compensator 6 may receive the common voltage affectedby the unspecified noise through a feedback line, and generate acompensated common voltage from the received common voltage to supplythe generated common voltage to the common voltage line VcomL of thedisplay panel 1 through the common voltage supply line. For example theunspecified noise by which the common voltage is affected may be thegate signals of the gate lines, or external static electricity.

The first common voltage compensation circuit 6 a may receive a commonvoltage through a first feedback line FL1 and supply the compensatedcommon voltage to the common voltage line VcomL of the display panel 1through a first common voltage supply line VSL1. The first feedback lineFL1 and the first common voltage supply line VSL1 may be coupled to thecommon voltage line VcomL at an upper left portion of the display panel1.

The second common voltage compensation circuit 6 b may receive a commonvoltage through a second feedback line FL2 and supply the compensatedcommon voltage to the common voltage line VcomL of the display panel 1through a second common voltage supply line VSL2. The second feedbackline FL2 and the second common voltage supply line VSL2 may be coupledto the common voltage line VcomL at a lower left portion of the displaypanel 1.

The third common voltage compensation circuit 6 c may receive a commonvoltage through a third feedback line FL3 and supply the compensatedcommon voltage to the common voltage line VcomL of the display panel 1through a third common voltage supply line VSL3. The third feedback lineFL3 and the third common voltage supply line VSL3 may be coupled to thecommon voltage line VcomL at an upper right portion of the display panel1.

The fourth common voltage compensation circuit 6 d may receive a commonvoltage through a fourth feedback line FL4 and supply the compensatedcommon voltage to the common voltage line VcomL of the display panel 1through a fourth common voltage supply line VSL4. The fourth feedbackline FL4 and the fourth common voltage supply line VSL4 may be coupledto the common voltage line VcomL at a lower right portion of the displaypanel 1.

In this case, the first and third feedback lines FL1 and FL3 and thefirst and third common voltage supply lines VSL1 and VSL3 may be formedas a line on glass type and coupled to the common voltage line VcomL atthe upper left and right portions of the display panel 1. Also, thesecond and fourth feedback lines FL2 and FL4 and the second and fourthcommon voltage supply lines VSL2 and VSL4 may be coupled to the commonvoltage line VcomL at the lower left and right portions of the displaypanel 1 by passing through the gate circuit films 3.

Each of the second and fourth feedback lines FL2 and FL4 and the secondand fourth common voltage supply lines VSL2 and VSL4 has a longer lengththan that of each of the first and third feedback lines FL1 and FL3 andthe first and third common voltage supply lines VSL1 and VSL3.Therefore, a problem occurs in that there is a great difference betweeneach resistance of the second and fourth feedback lines FL2 and FL4 andthe second and fourth common voltage supply lines VSL2 and VSL4 and eachresistance of the first and third feedback lines FL1 and FL3 and thefirst and third common voltage supply lines VSL1 and VSL3.

Therefore, a difference between the common voltage from the second andfourth feedback lines FL2 and FL4 and the second and fourth commonvoltage supply lines VSL2 and VSL4 and the common voltage from the firstand third feedback lines FL1 and FL3 and the first and third commonvoltage supply lines VSL1 and VSL3 may occur. That is, it is desirableto maintain the common voltage to one level voltage for driving theliquid crystal display, but the common voltage may not be maintained tothe one level voltage.

To reduce each resistance of the second and fourth feedback lines FL2and FL4 and the second and fourth common voltage supply lines VSL2 andVSL4, as shown in FIG. 2, a gate printed circuit board 8 connected tothe gate flexible film 3 may also be provided. In this case, because thesecond and fourth feedback lines FL2 and FL4 and the second and fourthcommon voltage supply lines VSL2 and VSL4 are coupled to the commonvoltage line VcomL at the lower left and right portions of the displaypanel 1 after being routed through the gate printed circuit board 8,each length of the second and fourth feedback lines FL2 and FL4 and thesecond and fourth common voltage supply lines VSL2 and VSL4 may bereduced. Therefore, each resistance of the second and fourth feedbacklines FL2 and FL4 and the second and fourth common voltage supply linesVSL2 and VSL4 may be reduced, whereby the difference between eachresistance of the second and fourth feedback lines FL2 and FL4 and thesecond and fourth common voltage supply lines VSL2 and VSL4 and eachresistance of the first and third feedback lines FL1 and FL3 and thefirst and third common voltage supply lines VSL1 and VSL3 may bereduced. However, a problem occurs in that the device cost is increasedbecause the gate printed circuit board 8 is added.

SUMMARY OF THE DISCLOSURE

Accordingly, the present invention is directed to a liquid crystaldisplay that substantially obviates one or more problems due tolimitations and disadvantages of the related art.

An advantage of the present invention is to provide a liquid crystaldisplay that may reduce a length of a line for connecting a commonvoltage supply circuit with a common voltage line provided at anopposite side of a lower substrate to which a source flexible film isattached.

Additional advantages and features of the invention will be set forth inpart in the description which follows and in part will become apparentto those having ordinary skill in the art upon examination of thefollowing or may be learned from practice of the invention. Theobjectives and other advantages of the invention may be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is an exemplary view illustrating a liquid crystal display of theprior art;

FIG. 2 is another exemplary view illustrating a liquid crystal displayof the prior art;

FIG. 3 is an exploded perspective view illustrating a liquid crystaldisplay according to the embodiment of the present invention;

FIG. 4 is an exemplary view illustrating a lower substrate, gateflexible films and source flexible films attached onto the lowersubstrate, a common voltage line provided on the lower substrate, commonvoltage supply lines and feedback lines;

FIG. 5 is a circuit view illustrating an example of a common voltagecompensation circuit of FIG. 4;

FIG. 6 is a plane view illustrating a liquid crystal display accordingto the embodiment of the present invention;

FIG. 7 is a rear view illustrating a liquid crystal display according tothe embodiment of the present invention;

FIG. 8 is a side view illustrating an example of a portion A of FIGS. 6and 7;

FIG. 9 is a cross-sectional view illustrating II-II′ of FIG. 6 and FIG.7;

FIG. 10 is a cross-sectional view illustrating I-I′ of FIG. 7;

FIGS. 11A and 11B are perspective views illustrating examples of aconnection structure between a first line cable of FIG. 7 and a firstconnection terminal of a circuit board;

FIG. 12 is a side view illustrating example of a portion A of FIG. 5;and

FIG. 13 is a cross-sectional view of FIG. 6.

DETAILED DESCRIPTION OF THE DISCLOSURE

Reference will now be made in detail to the exemplary embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

The terms described in the specification should be understood asfollows.

As used herein, the singular forms “a”, “an”, and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “first” and “second” are for differentiating oneelement from the other element, and these elements should not be limitedby these terms. It will be further understood that the terms“comprises”, “comprising,”, “has”, “having”, “includes”, and/or“including”, when used herein, specify the presence of stated features,integers, steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The term “at least one” should be understood as including anyand all combinations of one or more of the associated listed items. Forexample, the meaning of “at least one of a first item, a second item,and a third item” denotes the combination of all items proposed from twoor more of the first item, the second item, and the third item as wellas the first item, the second item, or the third item. The term “on”should be construed as including a case where one element is formed at atop of another element and moreover a case where a third element isdisposed therebetween.

Hereinafter, a liquid crystal display according to the embodiments ofthe present invention will be described in detail with reference to theaccompanying drawings.

FIG. 3 is an exploded perspective view illustrating a liquid crystaldisplay according to the embodiment of the present invention. Referringto FIG. 3, the liquid crystal display according to the embodiment of thepresent invention includes a display panel 100, a driving circuit unitfor driving the display panel 100, a backlight unit 300, and a guide andcase member 410, 420, 430.

The display panel 100 includes a lower substrate 110, an upper substrate120, and a liquid crystal layer between the lower substrate 110 and theupper substrate 120. The lower substrate 110 and the upper substrate 120may be glass or plastic.

The lower substrate 110 may be larger than the upper substrate 120. Gateflexible films 220 and source flexible films 240 may be attached to anupper corner of the lower substrate 110, which is not covered by theupper substrate 120.

The lower substrate 110 of the display panel 100 may include data lines,gate lines crossing the data lines, and a common voltage line. Pixelsmay be arranged in the display panel 100 in a matrix with a crossingstructure of the data lines and the gate lines. Each of the pixelssupplies data voltages of the data lines to a pixel electrode inresponse to gate signals of the gate lines. For this reason, each of thepixels controls transmittance of the light entering from a backlightunit by driving a liquid crystal of a liquid crystal layer through anelectric field generated by a potential difference between the datavoltage supplied to the pixel electrode and a common voltage supplied toa common electrode through a common voltage line.

The upper substrate 120 of the display panel 100 may include a blackmatrix and a color filter. However, if the display panel 100 is formedin a color filter on TFT (COT) array, the black matrix and the colorfilter may be on the lower substrate 110. The common electrode may be onthe upper substrate 120 in a vertical electric field driving mode suchas a twisted nematic (TN) mode and a vertical alignment (VA) mode, ormay be on the lower substrate 110 in a horizontal electric field drivingmode such as an in plane switching (IPS) mode and a fringe fieldswitching (FFS) mode. A polarizing panel may be attached to each of thelower substrate 110 and the upper substrate 120 of the display panel100, and an alignment film for setting a pre-tilt angle of the liquidcrystal may be formed on an inner surface of the substrates adjacent tothe liquid crystal.

The driving circuits unit includes gate driving circuits 210, gateflexible films 220, source driving circuits 230, source flexible films240, common voltage compensation circuits 250, a circuit board 260, anda light source driving unit 270.

The gate driving circuits 210 supply the gate signals to the gate linesof the lower substrate 110. If a driving chip is used as each of thegate driving circuits 210, each gate driving circuit 210 may be mountedon the gate flexible film 220 in a chip on film (COF) mode. The gateflexible films 220 may be attached to a corner of the lower substrate110, which is not covered by the upper substrate 120. Alternatively, thegate driving circuit 210 may be formed directly on the lower substrate110 in a gate driver in panel (GIP) mode. In this case, the gateflexible films 220 may be omitted.

The source driving circuits 230 supply the data voltages to the datalines of the lower substrate 110. If a driving chip is used as each ofthe source driving circuits 230, each source driving circuit 230 may bemounted on the source flexible film 240 in a chip on film (COF) mode.Alternatively, the source driving circuits 230 may be adhered to thelower substrate 110 in a chip on glass (COG) or chip on plastic (COP)mode. The source flexible films 240 may be attached to a corner of thelower substrate 110, which is not covered by the upper substrate 120,and the circuit board 260.

The common voltage may be affected by unspecified noise generated in thedisplay panel 1, and the common voltage compensation circuits 250 arefor compensating for the common voltage affected by the noise. Each ofthe common voltage compensation circuits 250 receives the common voltagefed back from the common voltage lines of the display panel 100, andsupplies the common voltage of which noise is compensated using thefeedback common voltage, to the common voltage line of the display panel100. The common voltage compensation circuits 250 will be describedlater in detail with reference to FIGS. 4 and 5. The common voltagecompensation circuits 250 may be mounted on the circuit board 260. Thecircuit board 260 may be attached to the source flexible films 240. Aprinted circuit board may be used as the circuit board 260.

The light source driving unit 270 includes a light source drivingcircuit 271 and a light source circuit board 272. The light sourcedriving circuit 271 supplies driving current to light sources 310 togenerate light. The light source driving circuit 271 may be mounted onthe light source circuit board 272. Alternatively, the light sourcedriving circuit 271 may be mounted on the circuit board 260. In thiscase, the light source circuit board 272 may be omitted.

The driving circuit unit may include a timing control circuit and acontrol circuit board on which the timing control circuit is mounted. Inthis case, the control circuit board may be coupled to the circuit board260 through a predetermined flexible cable.

The backlight unit 300 includes the light sources 310, a light sourcecircuit board 320, a light guide panel 330, a reflective sheet 340, andoptical sheets 350. The backlight unit 300 irradiates light to thedisplay panel 100 by converting the light from the light sources 310 toa uniform surface light source through the light guide panel 330 and theoptical sheets 350. Although the backlight unit 300 is illustrated as anedge type in FIG. 3, it is to be understood that the backlight unit maybe a direct type without limitation to the example of FIG. 3.

Light emitting diodes may be used as the light sources 310. The lightsources 310 are arranged on at least one side of the light guide panel330 and irradiate light to the side of the light guide panel 330. Thelight sources 310 are mounted on the light source circuit board 320 andare driven by the light source driving circuit 271. The light sourcecircuit board 320 is coupled to the light source driving unit 270.

The light guide panel 330 converts light from the light sources 310 to asurface light source and irradiates the surface light source to thedisplay panel 100. The reflective sheet 340 is arranged at a lowersurface of the light guide panel 330 and reflects the light, which isdirected from the light guide panel 330 toward the lower part of thelight guide panel 330, toward the display panel 100.

The optical sheets 350 are arranged between the light guide panel 330and the display panel 100. The optical sheets 350 include one or moreprism sheets and one or more diffusion sheets to diffuse the lightentering from the light guide panel 330 and collimate the light to alight incident surface of the display panel 100 at a substantiallyperpendicular angle. Also, the optical sheets 350 may include abrightness enhancement film.

The guide and case member includes a bottom cover 410, a guide frame420, and a top case 430.

The bottom cover 410 may be made of metal in a rectangular frame andsurround a side and a bottom of the backlight unit 300 as shown in FIG.9. The bottom cover 410 may be made of a steel sheet of high strength,for example, electro-galvanized sheet (EGI), steel use stainless (SUS),Galvarium (SGLC), aluminum coated steel sheet (ALCOSTA), and tin platedsteel sheet (SPTE).

As illustrated in FIG. 9, the guide frame 420 protects the display panel100 by supporting the lower substrate 110 of the display panel 100. Theguide frame 420 may partially surround the side and bottom of the lowersubstrate 110. The lower substrate 110 of the display panel 100 may beattached to the guide frame 420 by using a double sided adhesive tape421. The double sided adhesive tape 421 may also include a buffer memberto protect the lower substrate 110 from impact.

The guide frame 420 may be fixed by being secured to the bottom cover410. The guide frame 420 may be a rectangular frame, made from plastic,etc. in which glass fiber is mixed with synthetic resin such aspolycarbonate, or may be made of steel use stainless (SUS).

The top case 430 surrounds the corner of the display panel 100, an uppersurface and a side of the guide frame 420, and a side and a partiallower surface of the bottom cover 410. The top case 430 may be made ofelectro-galvanized sheet (EGI), steel use stainless (SUS), etc. The topcase 430 may be fixed to the guide frame 420 by a hook or screw.

FIG. 4 is an exemplary view illustrating a lower substrate, gateflexible films and source flexible films attached onto the lowersubstrate, a common voltage line on the lower substrate, common voltagesupply lines, and feedback lines. In FIG. 4, for convenience ofdescription, the lower substrate 110, gate flexible films 220 on whichthe gate driving circuits 210 are mounted, source flexible films 240 onwhich the source driving circuits 230 are mounted, common voltagecompensation units 251, 252, 253, and 254, connection terminals 255 and256, a circuit board 260, the common voltage line VcomL, common voltagesupply lines VSL1, VSL2, VSL3, and VSL4, and feedback lines FL1, FL2,FL3, and FL4 are only shown.

Referring to FIG. 4, the common voltage line VcomL is on the lowersubstrate 110. The common voltage line VcomL may include a plurality offirst lines in parallel along a first direction, and a plurality ofsecond lines coupled to the plurality of first lines and in parallelalong a second direction crossing the first direction. That is, becausethe common voltage line VcomL may be in a mesh structure as shown inFIG. 4, a potential of the common voltage of the common voltage lineVcomL may be uniform regardless of the location of the lower substrate110. Here, the first direction may be parallel with the gate lines, andthe second direction may be parallel with the data lines. The meshstructure denotes a net structure, thus the common voltage line VcomLhaving the mesh structure denotes that the common voltage line VcomL isformed in direction of both the gate lines and the data lines.

The first common voltage compensation circuit 251 may be coupled to thefirst common voltage supply line VSL1 and the first feedback line FL1.The first common voltage supply line VSL1 and the first feedback lineFL1 may be on the circuit board 260. The source flexible film 240, andthe lower substrate 110, and may be coupled to the common voltage lineVcomL at one side of the lower substrate to which the source flexiblefilm 240 is attached. In FIG. 4, the first common voltage supply lineVSL1 and the first feedback line FL1 are coupled to the common voltageline VcomL at an upper side (specifically, upper left side) of the lowersubstrate 110 to which the source flexible film 240 is attached. As aresult, the first common voltage compensation circuit 251 may receivethe common voltage of the common voltage line VcomL affected byunspecified noise generated in the display panel 100, the common voltagebeing fed back from the first feedback line FL1, and may output thecompensated common voltage through the first common voltage supply lineVSL1 to the common voltage line VcomL.

The second common voltage compensation circuit 252 may be coupled to thesecond common voltage supply line VSL2 and the second feedback line FL2.The second common voltage supply line VSL2 and the second feedback lineFL2 may be on the circuit board 260. The source flexible film 240, andthe lower substrate 110, and may be coupled to the common voltage lineVcomL at one side of the lower substrate to which the source flexiblefilm 240 is attached. In FIG. 4, the second common voltage supply lineVSL2 and the second feedback line FL2 are coupled to the common voltageline VcomL at an upper side (specifically, upper right side) of thelower substrate 110 adjacent to the circuit board 260. As a result, thesecond common voltage compensation circuit 252 may receive the commonvoltage of the common voltage line VcomL affected by unspecified noisegenerated in the display panel 100, the common voltage being fed backfrom the second feedback line FL2, and may output the compensated commonvoltage through the second common voltage supply line VSL2 to the commonvoltage line VcomL.

The third common voltage compensation circuit 253 may be coupled to thethird common voltage supply line VSL3 and the third feedback line FL3.The third common voltage supply line VSL3 and the third feedback lineFL3 are coupled to the first connection terminal 255 on the circuitboard 260. The first connection terminal 255 may be coupled to the firstline cable 510. The first line cable 510 may be on the lower surface andside of the bottom cover, the side and upper surface of the guide frame,and the upper surface of the lower substrate 110. Therefore, the firstline cable 510 coupled to the first connection terminal 255 may becoupled to the common voltage line VcomL at an opposite side of thelower substrate to which the source flexible film 240 is attached, bypassing the lower surface and side of the bottom cover, the side andupper surface of the guide frame, and the upper surface of the lowersubstrate 110. In FIG. 4, the first line cable 510 is coupled to thecommon voltage line VcomL at a lower side (specifically, lower leftside) which is an opposite side of the upper side of the lower substrate110 to which the source flexible film 240 is attached. The first linecable 510 will be described later in detail with reference to FIGS. 7 to13. As a result, the third common voltage compensation circuit 253 mayreceive the common voltage of the common voltage line VcomL affected byunspecified noise generated in the display panel 100, the common voltagebeing fed back through the first line cable 510, the first connectionterminal 255 and the third feedback line FL3, and may output thecompensated common voltage through the third common voltage supply lineVSL3, the first connection terminal 255 and the first line cable 510 tothe common voltage line VcomL.

The fourth common voltage compensation circuit 254 may be coupled to thefourth common voltage supply line VSL4 and the fourth feedback line FL4.As illustrated, the fourth common voltage supply line VSL4 and thefourth feedback line FL4 are coupled to the second connection terminal256 on the circuit board 260. The second connection terminal 256 may becoupled to the second line cable 520. The second line cable 520 may beon the lower surface and side of the bottom cover, the side and uppersurface of the guide frame, and the upper surface of the lower substrate110. Therefore, the second line cable 520 coupled to the secondconnection terminal 256 may be coupled to the common voltage line VcomLat an opposite side of the lower substrate to which the source flexiblefilm 240 is attached, by passing the lower surface and the side of thebottom cover, the side and upper surface of the guide frame, and theupper surface of the lower substrate 110. In FIG. 4, the second linecable 520 is coupled to the common voltage line VcomL at a lower side(specifically, lower left side) which is an opposite side of the upperside of the lower substrate 110 to which the source flexible film 240 isattached. The second line cable 520 will be described later in detailwith reference to FIGS. 7 to 13. As a result, the fourth common voltagecompensation circuit 254 may receive the common voltage of the commonvoltage line VcomL affected by unspecified noise generated in thedisplay panel 100, the common voltage being fed back through the secondline cable 520, the second connection terminal 256 and the fourthfeedback line FL4, and may output the compensated common voltage throughthe fourth common voltage supply line VSL4, the second connectionterminal 256 and the first line cable 520 to the common voltage lineVcomL.

As described above, according to the embodiment, the common voltagesupply circuit and the connection terminal coupled thereto are on thecircuit board 260, and the line cable coupled to the connection terminalis coupled to the common voltage line VcomL at an opposite side of thelower substrate to which the source flexible film 240 is attached. As aresult, in the embodiment, the length of the line for connecting thecommon voltage supply circuit with the common voltage line VcomL at anopposite side of the lower substrate to which the source flexible filmis attached may be reduced. Therefore, resistance of the line forconnecting the common voltage supply circuit with the common voltageline VcomL at an opposite side of the lower substrate to which thesource flexible film 240 is attached may be reduced. Also, because thegate printed circuit board attached to the gate flexible films 220 isnot included in the embodiment, the cost associated with the gateprinted circuit board may be eliminated.

FIG. 5 is a circuit schematic illustrating an example of a commonvoltage compensation circuit of FIG. 4. Although each of the first tofourth common compensation circuits 251, 252, 253, and 254 may be asshown in FIG. 5, it is to be understood that each of the first to fourthcommon compensation circuits is not limited to the example of FIG. 5.That is, each of the first to fourth common compensation circuits 251,252, 253, and 254 may output a compensated common voltage by using othercircuits which are already known.

Referring to FIG. 5, each of the first to fourth common compensationcircuits 251, 252, 253, and 254 includes a first power input terminalVI1, a second power input terminal VI2, an output terminal VO, and aninverting amplifier 600.

The first power input terminal VI1 may be coupled to any one of thefirst to fourth feedback lines FL1, FL2, FL3, and FL4. That is, afeedback voltage is supplied to the first power input terminal VI1. Thecommon voltage may be affected by unspecified noise generated in thedisplay panel 100. Thus, the feedback voltage is the common voltageaffected by noise.

The second power input terminal VI2 may be coupled to a reference commonvoltage line to which a reference common voltage is supplied. That is,the reference common voltage may be supplied to the second power inputterminal VI2. The reference common voltage may be a direct currentvoltage input from a power supply source.

The common voltage output terminal VO may be coupled to any one of thefirst to fourth common voltage supply lines SVL1, SVL2, SVL3, and SVL4.That is, a compensated common voltage is output from the common voltageoutput terminal VO.

The inverting amplifier 600 includes an OP-AMP OP, a first resistor R1,and a second resistor R2. The OP-AMP OP includes a non-inverting inputterminal (+) coupled to the second power input terminal VI2, receiving areference common voltage which is a direct current power voltage, and aninverting input terminal (−) coupled to the first power input terminalVI1, receiving a feedback voltage. The first resistor R1 is coupledbetween the inverting input terminal (−) of the OP-AMP OP and the firstpower input terminal VI1. The second resistor R2 is coupled between theinverting input terminal (−) of the OP-AMP OP and the output terminal.

The inverting amplifier 600 compensates for a difference between thefeedback voltage input to the inverting input terminal (−) of the OP-AMPOP and the reference common voltage input to the non-inverting terminal(+) at a first amplifying ratio, and outputs the result value.

$\begin{matrix}{{CVcom} = {{VREF} + {\frac{{RV}\; 2}{{RV}\; 1} \times \left( {{VREF} - {VFB}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

In the Equation 1, Vout is the compensated common voltage output to theoutput terminal of the OP-AMP OP, VREF is the reference common voltageinput to the non-inverting input terminal (+), and VFB is the feedbackvoltage input to the inverting input terminal (−). RV1 is a resistancevalue of the first resistor R1, and RV2 is a resistance value of thesecond resistor R2.

As described above, each of the first to fourth common compensationcircuits 251, 252, 253, and 254 may generate a compensated commonvoltage CVcom, which is obtained by compensating for the common voltageaffected by noise, by using the feedback voltage corresponding to thecommon voltage affected by noise, the direct current reference commonvoltage VREF input from the power supply source, and output thegenerated common voltage.

FIG. 6 is a plane view illustrating a liquid crystal display accordingto the embodiment. FIG. 7 is a rear view illustrating a liquid crystaldisplay according to the embodiment. FIG. 8 is a side view illustratingan example of a portion A of FIGS. 6 and 7. FIG. 9 is a cross-sectionalview illustrating II-II′ of FIG. 6 and FIG. 7. In FIGS. 6 to 8, forconvenience of description, the gate driving circuits 210, the gateflexible films 220, and the top case 430 may be omitted.

In FIGS. 6 to 8, the source flexible films 240 are bent toward the rearsurface of the display panel 100. To reduce a bezel size of the liquidcrystal display, the source flexible films 240 are bent toward the rearsurface of the display panel 100 as shown in FIGS. 6 to 8. The bezel atan outer edge of the liquid crystal display and corresponds to anon-display area where images are not displayed.

Connection of the third common voltage compensation circuit 253, thethird common voltage supply line VSL3, the third feedback line FL3, thefirst connection terminal 255, the first line cable 510 and the commonvoltage line VcomL will be described in detail with reference to FIGS. 6to 9.

The third common voltage compensation circuit 253, the third commonvoltage supply line VSL3, the third feedback line FL3, and the firstconnection terminal 255 are on the circuit board 260. The first linecable 510 is on the lower surface and side of the bottom cover 410, theside and upper surface of the guide frame 420, and the upper surface ofthe lower substrate 110.

The third common voltage compensation circuit 253 is coupled to thethird common voltage supply line VSL3 and the third feedback line FL3.The third common voltage supply line VSL3 and the third feedback lineFL3 are coupled to the first connection terminal 255. That is, the thirdcommon voltage supply line VSL3 and the third feedback line FL3 connectthe third common voltage compensation circuit 253 with the firstconnection terminal 255.

The first connection terminal 255 may be coupled to the first line cable510. In more detail, the first line cable 510 may include a first line511 for receiving a compensation common voltage from the third commonvoltage supply line VSL3 through the first connection terminal 255 and asecond line 512 for supplying a feedback voltage to the third feedbackline FL3 through the first connection terminal 255. The connectionstructure of the first line cable 510 and the first connection terminal255 will be described later in detail with reference to FIGS. 11A and11B.

A flat flexible cable may be used as the first line cable 510. The firstline cable 510, as shown in FIG. 10, may include a first insulating film710 on the bottom cover 410, lines 720 and 730 on the first insulatingfilm 710, and a second insulating film 740 to cover the first insulatingfilm 710 and the lines 720 and 730. In FIG. 10, the lines 720 and 730may be the first and second lines 511 and 512.

The first line cable 510 coupled to the first connection terminal 255may be coupled to the common voltage line VcomL at an opposite side ofthe lower substrate 110 to which the source flexible film 240 isattached, by passing the lower surface and side of the bottom cover 410and the side and upper surface of the guide frame 420. The first linecable 510 may be coupled to the common voltage line VcomL on a corner ofthe lower substrate 110, which is not covered by the upper substrate120.

The first and second lines 511 and 512 may be exposed at one end of thefirst line cable 510 coupled to the common voltage line VcomL. In thiscase, the exposed first and second lines 511 and 512 may be coupled tothe common voltage line VcomL by soldering. Alternatively, the exposedfirst and second lines 511 and 512 may be coupled to the common voltageline VcomL through a conductive adhesive, a conductive adhesive tape, oran anisotropic conductive film. Moreover, an insulating tape 422 may beattached onto the first line cable 510 and the common voltage line VcomLas shown in FIG. 9.

As a result, the third common voltage compensation circuit 253 mayreceive the feedback voltage from the common voltage line VcomL throughthe second line 512 of the first line cable 510, the first connectionterminal 255 and the third feedback line FL3. Also, the third commonvoltage compensation circuit 253 may output the compensated commonvoltage to the common voltage line VcomL through the third commonvoltage supply line VSL3, the first connection terminal 255 and thefirst line 511 of the first line cable 510.

Next, connection of the fourth common voltage compensation circuit 254,the fourth common voltage supply line VSL4, the fourth feedback lineFL4, the second connection terminal 256, the second line cable 520 andthe common voltage line VcomL will be described in detail with referenceto FIGS. 6 to 9.

The fourth common voltage compensation circuit 254, the fourth commonvoltage supply line VSL4, the fourth feedback line FL4, and the secondconnection terminal 256 are on the circuit board 260. The second linecable 520 is on the lower surface and side of the bottom cover 410, theside and upper surface of the guide frame 420, and the lower substrate110. If the first line cable 510 is on one side of the bottom cover 410and one side of the guide frame 420, the second line cable 520 may be onthe other side of the bottom cover and the other side of the guide frame420.

The fourth common voltage compensation circuit 254 may be coupled to thefourth common voltage supply line VSL4 and the fourth feedback line FL4.The fourth common voltage supply line VSL4 and the fourth feedback lineFL4 are coupled to the second connection terminal 256. That is, thefourth common voltage supply line VSL4 and the fourth feedback line FL4connect the fourth common voltage compensation circuit 254 with thesecond connection terminal 256.

The second connection terminal 256 may be coupled to the second linecable 520. In more detail, the second line cable 520 may include a thirdline 521 for receiving a compensation common voltage from the fourthcommon voltage supply line VSL4 through the second connection terminal256 and a fourth line 522 for supplying a feedback voltage to the fourthfeedback line FL3 through the second connection terminal 256.

A flat flexible cable may be used as the second line cable 520. Similarto the first line cable 510, the second line cable 520, as shown in FIG.10, may include a first insulating film 710 on the bottom cover 410,lines 720 and 730 on the first insulating film 710, and a secondinsulating film 740 to cover the first insulating film 710 and the lines720 and 730. In FIG. 10, the lines 720 and 730 may be the third andfourth lines 521 and 522.

The second line cable 520 coupled to the second connection terminal 256is coupled to the common voltage line VcomL at an opposite side of thelower substrate 110 to which the source flexible film 240 is attached,by passing the lower surface and side of the bottom cover 410 and theside and upper surface of the guide frame 420. The second line cable 520may be coupled to the common voltage line VcomL on a corner of the lowersubstrate 110, which is not covered by the upper substrate 120.

The third and fourth lines 521 and 522 may be exposed at one end of thesecond line cable 520 coupled to the common voltage line VcomL. In thiscase, the exposed third and fourth lines 521 and 522 may be coupled tothe common voltage line VcomL by soldering. Alternatively, the exposedthird and fourth lines 521 and 522 may be coupled to the common voltageline VcomL through a conductive adhesive, a conductive adhesive tape, oran anisotropic conductive film. Moreover, an insulating tape 422 may beattached onto the second line cable 520 and the common voltage lineVcomL as shown in FIG. 9.

As a result, the fourth common voltage compensation circuit 254 mayreceive the feedback voltage from the common voltage line VcomL throughthe fourth line 522 of the second line cable 520, the second connectionterminal 256 and the fourth feedback line FL4. Also, the fourth commonvoltage compensation circuit 254 may output the compensated commonvoltage to the common voltage line VcomL through the fourth commonvoltage supply line VSL4, the second connection terminal 256 and thesecond line 521 of the second line cable 520.

FIGS. 11A and 11B are perspective views illustrating examples of aconnection structure between a first line cable of FIG. 7 and a firstconnection terminal of a circuit board. In FIG. 11A, a flat flexiblecable is used as the first line cable 510. In this case, the first linecable 510 may include first and second lines 511 and 512 and aninsulating material 513 that covers the first and second lines 511 and512.

Referring to FIG. 11A, a connector 510 c from which junction pins 510 aand 510 b are exposed may be at one end of the first line cable 510. Thefirst junction pin 510 a may be coupled to the first line 511, and thesecond junction pin 510 b may be coupled to the second line 512.

The first connection terminal 255 may include a connector insertion unit255 a to which the connector 510 c of the first line cable 510 isinserted. Junction terminals may be inside the connector insertion unit255 a. It is to be noted that the junction terminals are not shown inFIG. 11A.

As a result, as the connector 510 c at one end of the first line cable510 is inserted to the connector insertion unit 255 a of the firstconnection terminal 255, the junction pins 510 a and 510 b of the firstline cable 510 may be electrically coupled to the junction terminals.That is, in the embodiment, the connector 510 c having the junction pins510 a and 510 b are at one end of the first line cable 510, and theconnector insertion unit 255 a having junction terminals is at the firstconnection terminal 255, whereby the first line cable 510 may easily becoupled to the first connection terminal 255.

Because a connection structure of the second line cable 520 and thesecond connection terminal 256 may be configured in substantially thesame manner as the embodiment shown in FIG. 11A, its detaileddescription will be omitted.

FIG. 11B is a perspective view illustrating another example of aconnection structure between a first line cable of FIG. 7 and a firstconnection terminal of a circuit board. In FIG. 11B, a flat flexiblecable is used as the first line cable 510.

Referring to FIG. 11B, connection pins 510 d and 510 e made of aconductive material may be at one end of the first line cable 510. Ahole to which a fixed member may be inserted may be provided at each ofthe connection pins 510 d and 510 e. For example, as shown in FIG. 11B,a first hole H1 to which a first fixed member 810 may be inserted may beat the first connection pin 510 d, and a second hole H2 to which asecond fixed member 820 may be inserted may be at the second connectionpin 510 e. The first connection pin 510 d may be coupled to the firstline 511 and the second connection pin 510 e may be coupled to thesecond line 512. Although the first and second fixed members 810 and 820are screws as shown, it is to be understood that the first and secondfixed members are not limited to the example of FIG. 11B.

The first connection terminal 255 may include connection pins 255 b and255 c made of a conductive material. A hole, to which a fixed member maybe inserted, and which passes through the circuit board, may be providedat each of the connection pins 255 b and 255 c. For example, as shown inFIG. 11B, a third hole H3 to which the first fixed member 810 may beinserted may be provided at the third connection pin 255 b, and a fourthhole H4 to which the second fixed member 820 may be inserted may beprovided at the second connection pin 255 c. The third connection pin255 b may be coupled to the third common voltage line VSL3, and thefourth connection pin 255 c may be coupled to the third feedback lineFL3.

As a result, the first fixed member 810 is inserted to the first hole H1of the first connection pin 510 d and the third hole H3 of the thirdconnection pin 255 b and thus fixed to a fixed member insertion unit(not shown) provided at the bottom cover 410, whereby the firstconnection pin 510 d of the first line cable 510 may be coupled to thethird connection pin 255 b of the first connection terminal 255. Also,the second fixed member 820 is inserted to the second hole H2 of thesecond connection pin 510 e and the fourth hole H4 of the fourthconnection pin 255 d and thus fixed to the fixed member insertion unit(not shown) provided at the bottom cover 410, whereby the secondconnection pin 510 e of the first line cable 510 may be coupled to thefourth connection pin 255 c of the first connection terminal 255. Thatis, in the embodiment, the connection pin having a hole is provided atone end of the first line cable 510, and the first connection terminal255 has the connection pin having a hole, whereby the first line cable510 may easily be coupled to the first connection terminal 255 by usingthe fixed member.

Because a connection structure of the second line cable 520 and thesecond connection terminal 256 may be configured in substantially thesame manner as the embodiment shown in FIG. 11B, its detaileddescription will be omitted.

FIG. 12 is a side view illustrating another example of a portion A ofFIGS. 6 and 7. FIG. 13 is a cross-sectional view illustrating III-III′of FIG. 6 and FIG. 7. In FIG. 12, for convenience of description, thegate driving circuits 210, the gate flexible films 220, and the top case430 are omitted.

In FIGS. 6, 7, and 12, the source flexible films 240 are bent toward therear surface of the display panel 100. To reduce a bezel size of theliquid crystal display, the source flexible films 240 are bent towardthe rear surface of the display panel 100 as shown in FIGS. 6, 7, and12. The bezel is at an outer edge of the liquid crystal display andcorresponds to a non-display area where images are not displayed.

Connection of the third common voltage compensation circuit 253, thethird common voltage supply line VSL3, the third feedback line FL3, thefirst connection terminal 255, the first line cable 510, and the commonvoltage line VcomL will be described in detail with reference to FIGS.6, 7, 12, and 13.

The third common voltage compensation circuit 253, the third commonvoltage supply line VSL3, the third feedback line FL3, and the firstconnection terminal 255 are on the circuit board 260. The first linecable 510 is on the lower surface and side of the bottom cover 410, theside of the guide frame 420, a hole H formed in the guide frame 420, andthe lower substrate 110.

The third common voltage compensation circuit 253, the third commonvoltage supply line VSL3, the third feedback line FL3 and the firstconnection terminal 255, which are shown in FIGS. 6, 7, 12, and 13 aresubstantially the same as those described with reference to FIGS. 6 to9. Therefore, a detailed description of the third common voltagecompensation circuit 253, the third common voltage supply line VSL3, thethird feedback line FL3 and the first connection terminal 255, which areshown in FIGS. 6, 7, 12, and 13, will be omitted.

The first line cable 510 coupled to the first connection terminal 255may be coupled to the common voltage line VcomL at an opposite side ofthe lower substrate 110 to which the source flexible film 240 isattached, by passing the lower surface and side of the bottom cover 410and the side of the guide frame 420, and the hole H provided in theguide frame 420. If the guide frame 420 surrounds the side of the uppersubstrate 120 and a partial side and lower surface of the lowersubstrate 110, the hole H for passing through the first line cable 510may be included. For this reason, the first line cable 510 may becoupled to the common voltage line VcomL on a corner of the lowersubstrate 110, which is not covered by the upper substrate 120.

The first and second lines 511 and 512 may be exposed at one end of thefirst line cable 510 coupled to the common voltage line VcomL. In thiscase, the exposed first and second lines 511 and 512 may be coupled tothe common voltage line VcomL by soldering. Alternatively, the exposedfirst and second lines 511 and 512 may be coupled to the common voltageline VcomL through a conductive adhesive, a conductive adhesive tape, oran anisotropic conductive film. Moreover, an insulating tape 422 may beattached onto the first line cable 510 and the common voltage line VcomLas shown in FIG. 13.

As a result, the third common voltage compensation circuit 253 mayreceive the feedback voltage from the common voltage line VcomL throughthe second line 512 of the first line cable 510, the first connectionterminal 255, and the third feedback line FL3. Also, the third commonvoltage compensation circuit 253 may output the compensated commonvoltage to the common voltage line VcomL through the third commonvoltage supply line VSL3, the first connection terminal 255, and thefirst line 511 of the first line cable 510.

Connection of the fourth common voltage compensation circuit 254, thefourth common voltage supply line VSL4, the fourth feedback line FL4,the second connection terminal 256, the second line cable 520 and thecommon voltage line VcomL can be configured similarly to that of thethird common voltage compensation circuit 253 described above withreference to FIGS. 6, 7, 12, and 13.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the inventions. Thus, itis intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A display device, comprising: a display panelincluding a first substrate and a second substrate; a source driverflexible film attached to the second substrate; a source driver circuitattached to the source driver flexible film; a common voltage lineprovided on the second substrate; common voltage supply lines and commonvoltage feedback lines connected to the common voltage line; commonvoltage compensation circuits connected to the common voltage supplylines and common voltage feedback lines; and a guide frame, wherein thecommon voltage compensation circuits include a first circuit linecoupled to the common voltage line at an opposite side of the secondsubstrate to which the source driver flexible film is attached anddisposed on one side of the guide frame, and a second circuit line on another side of the guide frame.
 2. The display device of claim 1, whereinthe circuit line is routed through a hole in the guide frame.
 3. Thedisplay device of claim 1, further comprising a cover adjacent to theguide frame.
 4. The display device of claim 1, wherein two commonvoltage compensation circuits each include a cable line that is routedat a rear of the display panel to two connection terminals,respectively, on the source driver circuit.
 5. The display device ofclaim 1, wherein the common voltage line includes a plurality of firstlines parallel to each other along a first direction, and a plurality ofsecond lines coupled to the plurality of first lines, wherein the secondlines are parallel to each other along a second direction crossing thefirst direction.
 6. The display device of claim 1, wherein the commonvoltage compensation circuits include first to fourth common voltagecompensation circuits.
 7. The display device of claim 6, wherein each ofthe first to fourth common compensation circuits generate a compensatedcommon voltage, obtained by compensating for common voltage affected bynoise, using feedback voltage from the common voltage feedback linescorresponding to the common voltage affected by noise, and a directcurrent reference common voltage input from a power supply source, andoutput the compensated common voltage.
 8. The display device of claim 1,wherein at least one common voltage supply line and one common voltagefeedback line are routed through the source driver flexible film to acorresponding common voltage compensation circuit.
 9. The display deviceof claim 1, wherein the circuit line is a flexible film.
 10. The displaydevice of claim 1, wherein the display panel is a liquid crystaldisplay.
 11. The display device of claim 9, wherein the flexible filmincludes a connector with junction pins, wherein the connector isinserted into to a connection insertion unit of the connection terminal.12. The display device of claim 9, wherein the flexible film includes aconnector with junction pins that is coupled to connection pins of theconnection terminal by inserting a fixing member in holes of thejunction pins and the connection pins.
 13. A method of fabricating adisplay device, comprising: providing a display panel including a firstsubstrate and a second substrate; attaching a source driver flexiblefilm to the second substrate; attaching a source driver circuit to thesource driver flexible film; providing a common voltage line on thesecond substrate; connecting common voltage supply lines and commonvoltage feedback lines to the common voltage line; connecting commonvoltage compensation circuits to the common voltage supply lines and thecommon voltage feedback lines; providing a guide frame supporting thedisplay panel; and connecting the common voltage compensation circuitsincluding a first circuit line coupled to the common voltage line at anopposite side of the second substrate to which the source driverflexible film is attached and disposed on one side of a guide frame, anda second circuit line on an other side of the guide frame.
 14. Themethod of claim 13, further comprising routing the circuit line througha hole in the guide frame.
 15. The method of claim 13, furthercomprising: providing a cover adjacent to the guide frame.
 16. Themethod of claim 13, wherein at least one common voltage supply line andone common voltage feedback line is routed through the source driverflexible film to a corresponding common voltage compensation circuit.17. The method of claim 13, wherein the circuit line is a flexible film.18. The method of claim 13, wherein the display panel is a liquidcrystal display.
 19. A display device, comprising: a display panelincluding a first substrate and a second substrate; a source driverflexible film attached to the second substrate; a source driver circuitattached to the source driver flexible film; a common voltage lineprovided on the second substrate; common voltage supply lines and commonvoltage feedback lines connected to the common voltage line; commonvoltage compensation circuits connected to the common voltage supplylines and common voltage feedback lines; a circuit board connecting tothe source driver flexible film and disposed at a rear of the displaypanel; and a circuit line including one end connected to a connectionterminal of the circuit board and the other end connected to the commonvoltage line at an opposite side of the second substrate to which thesource driver flexible film is attached.